Till The World Ends by Britney Spears is in Ab at 132 beats per minute and runs 3:11 across 55 bars. It uses 3 chords — Cm, Eb, Ab. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? Till The World Ends guitar melody tab.